Help: How to convert binary from response to base64

  1. In response to a request, I receive a file
  2. I need to save it to a variable and then convert to base64

But: [function c] is saved to the data variable

const mark1 = (pm.response);
console.log(mark1.stream.toString('utf-8'));

To convert the byte stream to base64
console.log(btoa(mark1.stream));